Difficulty level: High School

Class time: 1 Hour

In this lesson, students will analyze data from solar magnetogram images collected over 25 years at the National Solar Observatory Vacuum Telescope at Kitt Peak, AZ. Students will log the latitudes of all visible active regions as a function of date for several days through the solar cycle. Plotting the data as a function of dates as a scatter plot graph should result in a Maunder "butterfly" diagram.

Teacher Note: you should have your class work collectively to log data for this activity. Your students may find it useful to view the QuickTime movie of Magnetograms which is included on the DASL disk; or, construct a movie of target years to make it easier to identify particularly active dates within the solar cycle. Your students will need to span slightly more than one solar cycle, 12 or 13 years would be ideal, for this activity.

You may consider assigning blocks of time to individual students, or pairs of students, to expedite the collection of data. If you have the time, have your students collect data for all active regions on the solar disk, once every two weeks for a period of six or so months. Pool and color code data by year when completed.

Student Note: Your teacher will either assign you a period of time through which you will collect data or permit you to determine your own set of image dates. To do this you can choose to view the Magnetogram QuickTime movie included on your DASL disk or construct a movie of your choosing for a target year within the solar rotation you and your class are studying. You must determine a range of dates before you begin this activity.

Find the first image in the range of dates you wish to work on from the list of files that appears. The file names indicate the year, month and date in the following format:

900121MA is the magnetogram png file for January 21, 1990.

Choose Plugins from the menu bar, Macros from the drop down box and Log Date, Time, Latitude and Longitude from the list of options that opens.

Quick Key Tip: You can also use the F6 key on your keyboard to activate this macro.

Choose the Scrolling tool from the menu bar. It is the icon that resembles a tiny hand. (See above.)

Below the tool bar the message: "(Click to log)" will appear. Move the index finger of the scrolling tool into the center of the active region and press the left mouse button to log your data.

This is the Log Results window that was generated for the active region shown above.

Choose OK.

A Results table will appear with date, time, latitude and longitude data for the active region.

Hit the F6 key and click on another active region. Choose OK and continue doing this until you have logged the data for each visible active region on the image.

Close your image and open another one, repeating this data collection until you have covered the range of dates and images you were assigned.

Quick Key Tip: You can also use the letter O key on your keyboard to view the files and select your next image.

When all data for the solar cycle of choice has been collected, students should pool their result tables and combine them into a single spreadsheet. Graph the latitude data as a function of date to produce a scatter plot of the data.

Students will notice that there are bands in both northern and southern hemispheres. At solar minimum, there will be some at high latitudes and some at low latitudes. The high latitude regions are part of the new cycle, and the low latitude regions are part of the previous cycle. During a cycle they progress toward the equator.